Rotatable work holder for articles to belapped or ground



Dec. 4, 1951 L. E. DONAHUE 2,577,312

ROTATABLE WORK HOLDER FOR ARTICLES TO BE LAPPED OR GROUND Filed July 30,1949 5 Sheets-Sheet l INV v TOR.

Dec. 4, 1951 E. DONAHUE 2,577,312

ROTATABLE WORK HOLDER FOR ARTICLES TO BE LAPPED 0R GROUND Filed July 30,1949 3 Sheets-Sheet 2 INVENTOR.

Dec. 4, 1951 L. E. DONAHUE 2,577,312

ROTATABLE WORK HOLDER FOR ARTICLES TO BE LAPPED OR GROUND Filed July 50,1949 3 Sheets-Sheet 3 IN VEN TOR.

Patented Dec. 4, 1951 UNITED STATES PATENT I oF-FicE ROTATABLEW-ORKHOEDER; FOR narrows I TO BELAPPED R eaopnn: Law Ed d D minic; ,jCi icfl'I, Fill; s-

si-gnor-"to Crane ra kin fficmoany; Chicago,

111., incorporation of Illinois ApplicationfJnly so, 1949,.fseria1No,107,788

This invention relates to work; hoidei-js' for article finishing devicessuch as lappiri'gl and grind.-

'ataprecise angle with respect to the axis of the article In any oneknown instance, the angle inust be held to within plus; eig t seconds,minus nothing, the article itself being hexagonal" in shape and.approximately /8? across the flats. The surface itself must be held't'oan opticialnatiness and must have a, relatively high polish. Lapping.or' abrading of "such surfaces obviously cannot be done. with ahandoperation except at prohibitive cost. The object of this inventionis to provide a work holder for" long thin objects having angifl'arly',disposed faces at one end thereof; said holder? being adapted to supportthe work relative; to a lapping platen at apre'ci's'ely held angle. I

Amore specific object orthis inventionisfto provide a rotatable workholder. for long thin 'obie'ctsof the type described in which thearticle's are'indivi'dually supported and: in which the ends to "beoperated upon are located in a common plane.- a

Afstillfurther object of'this inventionis awork holder for articles ofthe type described wherein means"an:v provided for clamping articlesinthe holdehthe clampingjrneans.having a resilient separating device toenablethe operator to insert the articles into the device or remove themtherefrom. f a

Yet'another objector this invention is to pro vide a means'for locatingarticles in a work holderwith their ends projecting beyond a planeslirface on the Work holder at precisely the same distance so that theends j are all located'ina planewhioh is parallel to the said surface.

These and other objects andieatures of this invention will becomeapparent fromthe follow.- ing description when taken together with. theaccompa'nyingdrawings", in-which:

Fig: 1.is an enlarged fragmentary viewer-an article to which thisinvention is particularly applicable; the critical angularly disposedsurface thereof being shown for purposesof il'lustr'ation;

Fig; 2 is a fragmentarysection through atlapping 'machine havingarotatable lapping platen and/supporting" a work holder made inaccordance' with this invention;

Fig. 3 is an enlarged plan view of the work holderof this invention;

'4 is a section through the Work holder oi -Fig. a'taken along'lihetc'thereoi; and

2 Claims. ((31; 51:21?

' Fig. 51 is, an elevation through a; work holder and a positioningmeans for the articles to be snpported by the work holder; the.positioning means being shown insection.

Referring now to: Fig. 1, the article chosen for inn" ratio is comprisedof a thin hexagonal rod 10, ratio of the thickness taken across. thehatsto the length being, roughly; 1 to 25: The lower end off'theirodisprovided three fiat urfaces l l formed in such a manner that theyintersect in lines which are co'ntinuationsi of' arternateisectionsof'the rod. The angle a? between the surface H and an edge lz'isexceed.- ingl'y critical and must be held" to withinvplu's eightseconds, minus nothing. The surfaces 'll must be perfectly natjand musthave a high polish. I

The fixture for holding a plurality of such rods 10 while" the" criticalsurfaces. H are" being Tapped is'shown at [31in Fig. '2. Said fiicturj'eI3 is provided with a central opening M into which projects an axiallyslidab'lepin l5 sup.- ported in a frame IE" of a lapping machine,preferably of the type disclosed" in a copendjing'app'lrcation"xof"'Earl J. Bollard, Serial No. 14,619,

fi'led' IVIarc'h IZ'; 1-948, which issued as Patent No. 2,585,590,dated-"August 28, 1951'. Said machine is provided with a rotatablejshaftH' to which issec1rr"ed a iaten f8 having a lapped surface 1'9 whichisyperfectly fiat"; Plate'n- It "i's'fof course rotatable with shaft H"so that asthe-p-laten rotates-past work 'hol'denlt, said work holderwin he "caused to rotate about pin- 15; thereby providing continuousmovement 'ofthe' pins over variousportions of the lap surface 19.'Ihed'e tails of the lappingimachine and ofthe-abrad'anh su plyingdeviceprr such'machine" are fully dis closed "in thes'aid' Bullardapplication and hence need-= not tie-elaborated upon here. It win beapparent, however,- that if a plurality of pins 10 are supp ortedinawork hol-der l3 whilethe work holder is-rctated; said pins mustall con-'tact the-platen surface I 9 simultaneously; other wise one "of pinswill-have a surface which is-diiterently'locatedfrom the surfaces on theremaining pins. =otlier words, the pinno't con t'a'ctingthelaip will notbe acted: "upon by the lap untii' the other pins have been attained orlalpp'ed to -the extent necessary to shorten them to aproximately thesize ofi-"the p'in not acted epon- It is' -contemplatedin theafore'saidBullar'd machine thatthe'Weig-ht of the fixture shafl 'be sumcienttcmaintain the articles in contact ith the lap surface and in additionShaILs'uppI the :req-u'is'itc pressure $6 secure-e; fSfl-IaI11Ziif1g8Ifi0m 'sible.

moving vertically with respect to lap platen l8 so that the pin |5 maybe withdrawn entirely from opening l4 when it is desired to' removefixture |3 from the lapping machine. A nob is provided on the end of pinl5 for this purpose.

Referring now to Figs. 3 and 4 for a detailed description of the workholder, there is shown a two-part device having a first part 2| ofdished form and a second part 22 adapted to fit within the first part.Said first part 2| has a bottom surface 23 preferably formed perfectlyfiat and outer and inner conical surfaces 24 and 25, re-

spectively. Said inner surface 25 is tapered at approximately thedesired angle a. A plurality of hexagonal openings 26 are formed in thefirst part 2| and are preferably reamed so as to be as accurate in formand inclination as pos- The form of the openings is such as to hold thepin l0 therein against turning. Thus it may be a square opening adaptedto engage oppositely disposed fiat sides of the rod, or it may be ahexagonal opening adapted to fit snugly each of thesides of the rod.

' The disposition of the openings 26 in part 2| is such that surface 25intersects some part of the opening, preferably below a median line'drawn through the opening. This leaves a groove '21 in part 2| which isan extension of opening 26. Thus rod l0 may be located in the workholder at any desired angle with respect to surface 23 by theinclination of opening 26 and its grooved extension 21. The inclinationof rod it], however, produces a downward component of force on the rodand it is quite apt to move "axially in the opening 26 unless itsposition relative to part 2| is fixed. a

The means for fixing rod ID in part 2| is the second part 22 which isformed with grooves 28 similar to grooves 21 in form so that by clampingpart 22 to part 2| with only the grooves28 of part 22 contacting rodsH), the latter will be held in place against groove 2'! and will notmove ,axially therein. 7

The clamping means is comprised additionally of a bolt '29 having a head30 abutting on a rece'ssed shoulder 3| on part 2| and having a shankportion 32 passing through openings 33 and 34 in parts 2| and 22;respectively. The upper end of bolt 29 is threaded as shown at 25 toreceive a wing-nut 36 adapted to advance along threads into contact witha washer 31 adjacent the upper surface 38 of part 22. Thus by advancingwing-nut 36 on bolt 29, part 22 is clamped against part 2| through therods l0. When so clamped, the two parts and the rods form a rigidstructure which may be handled as a unit and slid over the pin l5 of thelapping machine as hereinabove described.

It is noted from Fig. 3 that a plurality of rods may be operated upon atthe same time with the work holder of this invention. The rods aredisposed along radii so as to resemble the spokes of a wheel.

., When serting rod l i t O fk h der.

or when removing finished rods therefrom, it is desirable merely toseparate the two parts 2| and 22 without necessarily disassembling theentire work holder as would be the case if the wing-nut 36 werecompletely backed off threads 35. To facilitate a separation without acomplete disassembly, three equally spaced locating pins 39 areprovided, the pins passing through openings 40 and 4| in parts 2| and22, respectively. One end of each pin 39 may be press-fitted into one orthe other of the parts while the other end has merely a snug fit withthe remaining part so as to permit relative motion between the parts.The part with the snug fit, e. g., part 2|, may be provided with anenlarged opening 42 in which is disposed a spring 43 of such length andstrength as to hold part 22 spaced from part 2| when wing-nut 36 isbacked off threads 35 a predetermined distance. This separation is justsuflicient to permit the insertion of rods In between grooves 21 and 28and for the removal of such rods from the holder when they have beencompletely lapped.

As stated above, it is important that initially the ends of-the rods alllie on a common plane. This is desirable not only from the standpoint ofuniformity of results to be obtained, but because of the customaryslotted construction of lap surface l9. If one of the rods extendedinward farther than the remaining rods, it would then be compelled tosupport the weight of the holder and as it slides into a slot, the rodwill be caught on the edge of the slot and would damage either the lapor the rod, or both, depending on which is hardest. With all of the rodends in a common plane, the work holder is supported by all of the rodsso that as one of them passes over a slot, the position of the holderrelative to the lap surface I9 is not changed and therefore the rod endpasses over the slot without being pressed into it.

The means for locating the rods in the work holders so that the rod endsall lie in a common plane is shown in Fig. 5. It is comprised of a plate44 having a centrally located pin 45 adapted to enter the opening M inbolt 29, thereby definitely locating the work holder with respect toplate 44. The upper surface 46 of plate is preferably lapped orotherwise made perfectly fiat. Secured to the upper surface 46 is a ring(the surfaces 48 and 49 of which are lapped flat and parallel. Said ring41 is secured to plate 44 by a plurality of screws 50. The upper surface49 of ring 41 engages surface 23 of part 2| and thereby supports thework holder over plate 44. The thickness of ring 41 is equal to theaxial distance'which rods |0 are to extend beyond surface 23 on part 2|.The inner diameter of ring 41 is greater than the diameter of a circlecircumscribing the openings 46 at surface :3! so that the openings areunobstructed by ring When it is desired to load the work holder 5 withrods H), the holder is slid over pin 45 until it rests on ring 41. Withwing-nut 36 backed partially off bolt 29 so that the springs 43 are theend surfaces 'of:=..the rods have been completely lapped, the' wing-nutmay be backed off as before and the rods removed, turned, and thenreinserted in their respective spaces so that another surface on theends thereof may be lapped. This procedure iscontinued until allsurfaces have been lapped, whereupon the parts 2l,-22 are againseparated to permit a complete removal of the finished rods from thefixture and the insertion of other rods thereon.

It has been found that the work holder hereinabove described and thepositioning of means shown in Fig. 5 give excellent uniformity of resultcombined'with considerably increased production and the maintenance of ahigh degree of accuracy. Obviously the work holder is adapted for usewith other shapes of rods and various angles of surfaces to be formed onthe ends of the rods, from surfaces normal to the axes of the rods, tosurfacesat extremely acute angles with respect thereto; As described inthe aforementioned Bullard application, work holders of the type hereindescribed may Q her and contacting the objects over a substantial lengthof said objects, a hollow bolt passing through both members, and a nutfor the bolt for clamping the members together, thereby to clamp theobjects between the members, said hollow bolt being adapted to receivea, pivot pin about which the holder may rotate.

2. A rotatable holder for long thin objects as described in claim 1, andmeans for locating the 7 objects in the holder with the ends of theobjects extending a uniform amount beyond the holder, said meanscomprising a plate, a spacer ring on the plate adapted to contact theholder and locate the plate uniformly from the holder,

the ends of said objects extending beyond the holder and contacting theplate, and a pin on said plate extending into the hollow bolt to locatethe plate with respect to the holder.

a plurality of LAWRENCE EDWARD DONAHUE.

REFERENCES CITED The following references are of record in the file ofthis patent:

be used simultaneously with one lap platen,

thereby multiplying the production by the number of such holders used.

It is understood that the foregoing description is illustrative ofpreferred embodiments of this invention and that the scope of theinvention is not to be limited thereto, but is to be determined by theappended claims.

What is claimed is:

1. A rotatable holder for long thin objects of which the cross sectionis a regular polygon and the end surfaces of the objects are to befinished by lapping or the like, said holder comprising a dished memberhaving a substantially flat bot-.

tom and conical sides, said sides having grooves to receive a portion ofthe objects and said bottom having openings of the same cross section asthe said objects aligned with the grooves through which other portionsof the objects extend, a

second member adapted to fit into the first mem- UNITED STATES PATENTSNumber Name Date 1,227,498 Sleeper May 22, 1917 1,279,725 Liebmann Sept.24, 1918 1,405,474 Yehle Feb. 7, 1922 1,426,965 Crowther Aug. 22, 19221,763,647 Danner June 17, 1931 1,823,537 Saudreau Sept. 15, 19312,116,922 Bleasdale May 10, 1938 2,352,551 Kende et a1 June 27, 19442,389,069 Mascarenhas Nov. 13, 1945 2,466,610 Newman Apr. 5, 1949FOREIGN PATENTS Number Country Date 21,996 Great Britain of 1913 517,290France Dec. 17, 1920 674,027 Germany Apr. 3, 1939

